This is why Observatories are built on top of Mountains

It’s probably safe to assume that most of us understand that Space observatories are built at high altitudes where viewing conditions are better because the atmosphere is less dense. Sharp-witted photographer Rob Ratkowski created this clever visual aid to show how altitude makes huge differences to imaging the skies.

Effects of Seeing at Altitude copy

Science explainers like Ratkowski often have to find unique ways to demonstrate certain scientific reasoning. Using photography and just his index finger it becomes immediately apparent how viewing can be better depending on altitude.

Ratkowski told EPOD:

Astronomers are frequently asked why we have our observatories on high mountain tops. A big part of looking into deep space has to do with atmospheric transparency and freedom of particulates along with heat that causes blurring. A simple but effective understanding of this seeing is to put a finger at arm’s length in front of the Sun and observe the aureole that’s produced. Held at arm’s length, a finger tip subtends about one-half of a degree of sky – nearly the same amount of space that both the Sun and Moon take up. At sea level, observing is often compromised by the build up of heat, dust, moisture, haze, pollution, and aerosols that include ash and even salt. Higher up, there’s less of this to deal with since there’s less atmosphere to peer through. These three photos were taken on the Hawaiian island of Maui at (left to right) Baldwin Beach, Kula and Haleakala Observatory, respectively. The disk of the Sun is completely hidden by my index fingertip at 10,000 ft (about 3,050 m). Note, I can positively verify that my finger didn’t increase in size as a result of the thinner air.

Ratkowski told Phogotaphy that he works at NASA’s satellite laser ranging station for UHawaii Institute for Astronomy which requires him to be at altitude several times a week. As an example of how clear the skies are he shared one of his most recent photograph taken from the summit.

Nikon D511 w/Sigma 8mm, 45sec at f/5.6, ISO 1200

The fisheye shot not only shows the crystal clear skies above Hawaii, but the beautiful phenomena known as the zodiacal light – visible usually during the Summer months.



Rob Ratkowski‘s images used with explicit permission.


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